An edge illuminated photovoltaic device, also known as a vertical photovoltaic device, is a photovoltaic device, in which light illuminates a p-n junction through the edge of the device, i.e. in the direction substantially non-parallel, to the direction defined by the device's electrical contacts to the outer surface. One advantage of edge illuminated photovoltaic devices is elimination of the need for transparent front and/or back contacts. Another advantage is the ability to connect several of individual single junction photovoltaic cells in series to form a multijunction device. Such series connection capability can provide a high voltage, low current operation with a better compatibility to power processing loads and a high tolerance to series resistance values within the electrical system. Edge illumination photovoltaic devices are often designed for use with concentrating solar collectors. Edge illumination photovoltaic devices are disclosed, for example, in R. J. Soukup, Journal of Applied Physics, vol. 48, p. 440, 1977; C. Hu et. al. Journal of Applied Physics, vol. 48, p. 442, 1977; R. J. Soukup, Journal of Applied Physics, vol. 48, p. 445, 1977.
Two of the requirements for a commercial photovoltaic device are high efficiency and low cost. The inventor believes that one example of device that came close to satisfying these requirements is an edge illumination photovoltaic device by PhotoVolt, Inc., Strongsville, Ohio, (see e.g. B. L. Sater and N. D. Sater “High Voltage Silicon VMJ Solar Cells for up to 1000 Suns Intensities”, Photovoltaic Specialists Conference, 2002, Conference Record of the Twenty-Ninth IEEE, pp. 1019-1022; and U.S. Pat. Nos. 4,332,973, 4,409,422 and 4,516,314, all incorporated herein by reference in their entirety). Although low cost, non-optimized “working model” of this silicon based device can achieve nearly 20% efficiency at 332 suns (33.2 watts/cm2), the device's theoretical efficiency of >30% at 1000 suns was not attained due to manufacturing issues associated with metallization and fabrication of multiwafer stacks.
Thus, a need exists to develop alternative low cost methods for making edge illumination photovoltaic devices.